Why High Equity Valuations And Low Bond Yields Won’t (Necessarily) Break The 4% Rule

Why High Equity Valuations And Low Bond Yields Won’t (Necessarily) Break The 4% Rule

For nearly 30 years, the so-called ‘4% rule’ has been a starting point for retirement planning conversations between financial planners and their clients. But as equity valuations such as the Shiller CAPE ratio have ratcheted up to nearly all-time highs in recent years, with bond yields simultaneously reaching all-time lows (suggesting below-average future returns in both asset classes), some experts have questioned whether a 4% initial withdrawal rate will continue to be ‘safe’ in the future. A new white paper by Morningstar feeds into this speculation, with its much-publicized conclusion stating that, given today’s market conditions, the future safe withdrawal rate should be lowered to 3.3%.

The Morningstar paper’s key insight is that expectations for future safe withdrawal rates should be adjusted based on current market conditions (which other research has supported). Accordingly, the paper’s authors use forward-looking return projections to calculate their future safe withdrawal rate estimates. But the investment return assumptions that Morningstar used for its analysis were so low – with real returns averaging just 5.7% for equities and 0.5% (!) for fixed income over 30 years – that, if those projections were to come to pass, the next 30 years would be among the very worst market environments in U.S. history.

While such conservative return estimates might make sense over a 10- to 20-year time horizon (since research has shown that CAPE ratios are strongly predictive of returns over that time range), extending those assumptions out to 30 years is arguably unrealistic. This is because there is no precedent – even in other eras with high equity valuations – for 30-year returns that low (other than the period spanning the late 19th and early 20th centuries, when financial panics and global war created a far more tumultuous and unpredictable environment than the comparatively stable world today). In reality, markets tend to revert to the mean, meaning that even the periods with the worst safe withdrawal rates in history contained intervals of offsetting below- and above-average returns, causing each to end out with near-average returns over the full 30-year horizon.

In this way, Morningstar’s choice to focus on (historically low) 30-year returns for its analysis disregards the evidence of what really drives safe withdrawal rates, which is the sequence of returns. Because the periods that have tested the 4% rule in the past were not necessarily those with the worst 30-year returns, but those whose returns in the first 10-15 years were so bad that retirees needed to withdraw too much of their portfolio to be able to recover once conditions improved. So in reality, Morningstar’s results may have been more realistic if they had only forecast 15-year instead of 30-year returns, since the 15-year period is both easier to predict on current market data and more predictive of safe withdrawal rates.

Ultimately, however, Morningstar’s conservative return assumptions – which are comparable to some of the worst periods in the past 140 years – actually serve to highlight the strength of the 4% rule, which was created to withstand just those types of worst-case scenarios. Which means that, even if their historically low projections do come to pass, resulting in returns equal to the worst return scenarios in history, a 4% initial withdrawal rate would still hold up. And while today’s market conditions do merit caution (as there is reason to believe that the next 15 years could experience below-average portfolio returns), in reality, such conditions were precisely what the 4% rule was created for, to begin with!

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